Many actors play a role in air traffic management. They share common resources consisting especially of the airspace and one or more airport hubs. Of these actors, three groups occupy a vital position:                Air-traffic control;        Airports;        Airlines.        
These groups have different tasks and goals. These tasks and goals are sometimes complementary but they can also be contradictory. In particular, traffic control must provide for the security and separation of the flights, while the interest of the airlines is to ensure the best possible use of aircraft. Airports, for their part, apart from being concerned with the security aspects, seek maximum economic efficiency for their installations and more generally seek to receive high traffic.
Delay management is an example illustrating the problems encountered in air traffic or airport traffic. The IATA (International Air Traffic Association) recommends especially that an airline should inform the airport of arrival if it expects a delay of more than 15 minutes. The delay message is transmitted through a dedicated network, by telephone or by fax. However, the airport of arrival does not always know the time at which the aircraft will land. There may even be a domino effect, creating an accumulation of delays. A standard approach may indeed be as follows: technical staff waits at the arrival gate but, as the aircraft has still not arrived, the gate reserved for it is assigned to another aircraft or else the technical staff leaves in order to deal with another flight. The result is that, when the aircraft finally arrives, its reception infrastructure is no longer available. This will lead to an additional delay for the passengers, pending for example the availability of a new gate.
In Europe, certain estimates indicate that about 35% of flights are delayed and that the average delay is about 20 minutes. An average delay of this kind has a major domino effect. In other words, other additional delays, especially reaction times due to a late arrival of the aircraft, will get added to the initial delay and pile up.